Technical Abstract:
Nursery growers are seeking new sprayers that can discharge droplets uniformly within Taxus spp. canopies to obtain healthy and marketable plants. A custom-designed five-port, air-assist sprayer was investigated to improve spray penetration into taxus canopies in a production nursery. Air velocity profiles from nozzle outlets to 0.79 m below the nozzles were determined experimentally and mathematically. Spray deposits at top, middle and bottom of canopies were characterized using fluorescence detection, and were compared with two application rates. The air velocity decreased from 40.1 to 19.4 m/s when the distance from the orifice increased from 0.33 to 0.79 m. Variations of air velocities across the same level above the ground decreased as distance from the nozzle increased. Tests indicated that increasing application rate by 34% could increase spray deposition at the bottom of canopies by 42%. Spray deposits increased as the air velocity at target positions increased.